      program demo_isblank
      use M_strings, only : isblank
      implicit none
      integer                    :: i
      character(len=1),parameter :: string(*)=[(char(i),i=0,127)]
         write(*,'(*(g0,1x))')'ISXBLANK: ',&
         & iachar(pack( string, isblank(string) ))
      end program demo_isblank
